The present invention is directed to a framing jig for use in building construction and in particular to a portable framing jig which may be employed to frame various configurations of wall sections as well as roof trusses and similar structural components.
The wooden or metal frame construction of buildings requires the construction of various sub-assemblies such as wall sections and roof trusses. These structural sub-assemblies are typically constructed in place on the job site. Proper construction such that the sub-assemblies are properly dimensioned and square relies heavily on the skill of the individual craftsman. Non-uniformity in construction techniques is a feature of such manual construction. Furthermore such manual construction techniques are often time consuming.
One solution to these identified problems is prefabricated factory construction. While having many advantages of speed, economy and uniformity, factory prefabrication entails the transportation of bulky structural sub-assemblies from the factory to the job site, which is much less efficient than the transportation of lumber or steel.
It is known in the art to employ framing tables or jigs as construction aids in the prefabrication of wall sections, trusses and similar components. A jig typically includes a supporting surface or frame bed to support the various components of, for example, a wall section. There is then provided means for holding the various components in proper alignment for fastening together into the completed wall section. More specifically, a wall section would typically include a top plate or header in parallel relationship to a sill plate or bottom plate. A number of spaced parallel studs are placed between the top plate and the bottom plate. The studs are then nailed or otherwise fastened to the top plate and bottom plate to form the basic wall section. The basic wall section may be supplemented by additional components to form window and door openings. The jig also provides means for squaring up the components prior to assembly. Using a jig typically allows a wall section to be completed in less time, more accurately, and with fewer workers. Another advantage is that assembly can be conducted at a fixed height above ground which greatly eases the assembly process.
An example of such a jig is disclosed in U.S. Pat. No. 4,801,130 issued to Montgomery on Jan. 31, 1989 for "Framing Table Assembly." Montgomery discloses a framing table having longitudinally extending benches for horizontally supporting the top and bottom plates. Each bench is equipped with an array of flippers that may be pivotally positioned between a ready station and an active station. The spacing between the flippers at the active station may be narrowed to securely hold studs in position between the top and bottom plates.
It is also known in the art to provide portable jigs for use at construction sites. Such portable jigs provide many of the advantages of factory built construction while avoiding the complication of transportation of finished structural sub-assemblies from the factory to the job site. An example of a portable jig is disclosed in U.S. Pat. No. 4,629,171 issued to Judy, et al. on Dec. 16, 1986 for "Portable Jig for Assembling Prefabricated Building Structures." Judy discloses a jig for assembling a prefabricated building wall or similar structure. The jig includes a supporting frame and clamping members for forcing the top and bottom plates into engagement with the ends of the studs to assist in fastening the components together.
A problem not heretofore recognized in the use of jigs to assist in the construction of wood or metal frame sub-assemblies is that modern framing techniques have advanced beyond the traditional practice in which walls are constructed using a standard stud spacing and relatively simple arrangement of studs. For example, a builder may be required to alternate from a stud spacing of 24 inches on center to one of 16 inches on center, or even to 12 inches on center. Other spacings are, of course, possible although less common. In addition, the advent of energy efficiency concerns has led to the development of new framing arrangements such as staggered stud double walls. In this technique the wall thickness is no longer determined by the width of the typical 2.times.4 or 2.times.6 stud. Instead, the top and bottom plates become 2.times.6s or 2.times.8s or 2.times.12s or other suitable dimension. The studs are typically placed on 12 inch centers, however, the studs alternate between being placed toward the outer wall or toward the inner wall. The studs then present the appearance of defining two walls, one set of studs being on 24 inch centers toward the outer portion of the wall and the other set of studs staggered into the intervals between the first set of studs and positioned toward the inner wall, likewise on 24 inch centers. With this construction technique it is possible to place a great deal more insulation into the wall. This also allows the wiring to be sandwiched between the insulation with no holes drilled through the studing which eliminates air leakage at receptacle boxes. There is the additional advantage that there is no thermal bridging across the width of the wall since no single stud spans the entire width of the wall. While there are considerable advantages to the use of the staggered stud double wall, the construction of the staggered stud double wall is considerably more difficult than the construction of a traditional wall. While a traditional wall may be placed on a horizontal surface for assembly, the construction of a double wall requires some means for holding the alternating studs above the assembly surface. Manual framing therefore would require more persons to assist in the framing process with a great loss of economy.
In addition to the problems set forth above, the use of portable jigs at job sites implies that for maximum efficiency relative to the construction of wall sections or trusses at the factory, the portable jig must, to a considerable extent, carry the tools, equipment and materials available at the factory to the job site. There is thus a need to provide for a complete integrated system to maximize the efficiency of fabrication of structural sub-assemblies at the job site.